The transmission and storage of digitized video may require considerable bandwidth. The bandwidth requirements may be such that video cannot be transmitted in real time, for example, resulting in a poor user experience.
One way in which this problem may be addressed is through the compression of a video signal. This results in fewer bits per frame having to be transmitted, and therefore allows the transmission of a greater number of frames per unit time given a channel of limited capacity. There are several disadvantages that may come with video compression, however. One disadvantage is that the quality of the video received may be poor. Compression may result in less information being transmitted. The result is that the image, as reconstructed for the user, may be inferior.
As a result, there is an historical trade-off between video quality and the extent of video compression applied to a signal. Greater compression lowers the bandwidth requirement and allows a lower bit rate, but may result in a poor experience for the user. Less compression requires more bandwidth and a higher bit rate, but the user's viewing experience may be better.
The extent of video compression may be controlled by a bit rate control algorithm. Such an algorithm affects the amount of compression performed and therefore affects the trade-off between bandwidth consumption and video quality. Typically, a quantization parameter (QP) drives the extent of video compression in a bit rate control algorithm.
In the drawings, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.